In conventional networks, measurement of network convergence involves injecting probes throughout the network. Such techniques do not scale well and hence suffer from accuracy issues (not enough probes are sent to measure at a millisecond timescale) and completeness issues (probes cannot be sent on all the possible paths through the network). Also, probes may simply report of a problem without the ability to pin point its location and provide details for use in analyzing the root cause.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.